Tetrahydrofuran → (R*,R*)-alpha-2-propenyloxiraneethanol

Beteiligte Stoffe

Reaktionsschritte

n-Butyllithium, 129 mL (200 mmol), is added dropwise to a 0° C. solution of 1,6-heptadien-4-ol, 22.4 g (0.2 mol), in 200 mL of anhydrous tetrahydrofuran until the triphenylmethane indicator turned red. Carbon dioxide is then bubbled in for 30 minutes (lecture bottle carbon dioxide passed through drierite) and the light yellow solution is stirred for 30 minutes under a balloon of carbon dioxide. To this solution is added iodine, 101.4 g (0.4 mol), dissolved in ~200 mL of anhydrous tetrahydrofuran over 60 minutes. The mixture is allowed to warm to room temperature overnight, diluted with ethyl acetate, washed with 10% sodium bisulfite solution, saturated solution of sodium bicarbonate, brine, and dried (magnesium sulfate). The crude product is dissolved in 200 mL of methanol and 20 mL of water, cooled to 0° C. and 0.5 g of solid potassium carbonate is added. The mixture is vigorously stirred for six hours, filtered, concentrated, and partitioned between ethyl acetate and brine. After extracting the aqueous layer 2x with ethyl acetate, the combined organics are washed with brine and dried (magnesium sulfate). Flash chromatography (4:1 hexane-ethyl acetate) provides, after concentration in vacuo, 18 g of (R*,R*)-α-2-propenyloxiraneethanol. 200 MHz NMR (CDCl3) δ1.5-1.65 (m, 1H), 1.90 (dt, 1H, J=15, 4 Hz), 2.2 (m, 3H), 2.53 (m, 1H), 2.79 (m, 1H), 3.12 (m, 1H), 3.94 (m, 1H), 5.19 (m, 2H), 5.80 (m, 1H).

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